This invention pertains to an instrument pen and pen arm, and the combination thereof, all adapted for the convenient installation of a disposable marker in an instrument in which the marker body is located at some distance from the marker writing tip. In particular, this invention pertains to a disposable marker and mounting arm wherein the marker body, when mounted in an instrument, is not readily accessible and from which an extended length stylus tube projects to a writing location at an exposed face of the instrument.
Instruments for the recordation of variables such as temperature and the like utilize a variety of pen designs for actually tracing a line recording on a writing surface. Within the past fifteen years, pens of this type have been significantly improved with respect to reliability, ease of installation, and cost, primarily through the provision of disposable markers of various types, many of which are specifically configured for use in instruments of particular design.
As these instruments have become smaller and smaller, it has become increasingly difficult to provide pens having the attributes of reliability and ease of installation, even apart from cost. This difficulty is enhanced in pen designs developed for installations in which a plurality of pens may be used in conjunction with one another, i.e., the pens must necessarily pass over one another for tracing lines on a common writing surface. This is particularly true for pens used in those instruments in which the location of the writing surface is at an accessible face for easy reading, while the pen mounting means and the space provided for the pen reservoir body or ink supply is disposed at some distance from the writing surface, generally deep within the instrument and at a location relatively inaccessible for pen installation.
One type of disposable marker heretofore provided for that purpose comprises a relatively flat body (in which the ink reservoir is housed), adapted to pass over other like pens in a horizontal plane. Each such pen includes an elongated stylus tube extending forwardly from the body to the writing surface. In a marker of this type, the body also includes a slot for receiving a pen arm mounted to the bottom surface of the marker body; the pen arm extends forwardly in the slot of the marker body to a positioning stop at the forward end thereof. Conventionally, these pen arms have been relatively short and the markers have been relatively difficult to install. Installation is generally accomplished either by opening the instrument to permit accessibility to the rearward portion in which the pen body is mounted on the pen arm, or by careful manipulation of the pen rearwardly, using the stylus tube as the support means for the marker body as it is passed through the stylus tube opening and eventually piloted onto the pen arm for mating engagement with the slot provided on the marker body.
Other than the markers and pen arms described above, instrument marking systems with elongated pen arms are seen also for example in patents such as the following:
U.S. Pat. Nos. 2,176,777; 2,752,220; 2,800,385; 2,820,689; 3,163,491; 3,264,652; 3,311,920; 3,452,359.
However, it will be noticed that in each of these patents, either an extended arm is provided for the mounting at the forward end thereof of a relatively short length marker or marker element or an extended pen arm is utilized as the mounting for a flexible tube. Note U.S. Pat. No. 3,264,652, for example, in which the flexible tube is fastened to the elongated pen arm by adhesive strips 33, 34, and 35.
From the foregoing, it is apparent that there is a need for an improved design pen, pen arm, and combination thereof for use in those instrument marking systems wherein the ink reservoir body is to be located in a relatively inaccessible location and the writing tip associated therewith is connected by an elongated stylus tube, and wherein the pen and pen arm are adapted so that several of such pens may be used together and may pass over one another for writing on a common writing surface.
It is, therefore, the general object of the present invention to provide such a pen and pen arm and a combination of such a pen and pen arm adapted to mate with one another.